1. Field of the Invention
The present invention refers to a method of controlling a curve cutting device for cutting a textile web as well as to a curve cutting device for cutting a textile web.
2. Description of the Related Art
Quite generally, the present invention deals with the cutting of textile webs having a curve-shaped border. In a special case of use, the present invention deals with the automated pinking or burning out of curtains.
Specific types of curtains have a curve-shaped lower border extending along a curtain pattern. This lower border is typically produced by manual work by pinking the curtains or by burning them out. This is done by an operator who draws a curtain by hand across a table, which is provided with a glow cutting wire extending at right angles to said table, in such a way that the glow cutting wire travels through a socalled light gap in the pattern of the curtain while said curtain is moving relative to said glow cutting wire, whereby crosspieces extending across the light gap will be cut through. This work is, of course, time-consuming and troublesome.
German Utility Model 89 07 823.3 discloses a curve cutting device of the type mentioned at the beginning, which is used for automated pinking or burning out of curtains and the cutting head of which is moved to and fro by means of a driving device for moving the cutting head at right angles to the direction of movement of the curtain in accordance with detection signals of an optoelectronic detection device. The detection device works with a broad light beam incident essentially at right angles to the plane of the curtain, said light beam being reflected towards a guide sensor, which is not described in detail, by a reflecting curve cutting mark applied to the curtain at the desired cutting location. According to said German Utility Model, a guide sensor is thus able to recognize the position of the cutting head relative to the curve cutting mark applied to the curtain and to automatically guide said cutting head. This publication does not disclose any information on the nature of the structural design of the guide sensor. However, said known curve cutting device is, if it is actually possible to realize it in practice, in any case limited to the processing of textile webs or types of curtains having a reflecting mark woven into the curtain or applied thereto; said reflecting mark has to be provided at the location of the desired cut. In the case of most types of curtains it is impossible to weave-in or to apply such curve cutting marks for reasons of production engineering or it is undesirable for reasons of costs.
In view of the fact that the measure of weaving into the textile web reflecting curve cutting marks of the type required in connection with the German Utility Model assessed hereinbefore is normally not applicable, the socalled pinking or burning out of curtains, i.e. the separation of a strip of woven fabric lying below the intended lower border of a curve-shaped curtain, is carried out by hand even nowadays.
Up to now, it has been regarded as being impossible to automatize this cutting of patterns.
The prior, not-prepublished German patent application P 41 36 069.9, which is owned by the applicant, already describes a curve cutting device comprising a cutting head, a driving device for moving said cutting head at right angles to the direction of movement of the textile web and an optoelectronic detection device for detecting the position of the cutting head relative to the light gap of the textile web. The optoelectronic detection device comprises three light barriers which permit autotracking of the cutting head with respect to the light gap of the textile web by combining the respective signals in a suitable manner. Although this curve cutting device permits fully automatic burning out of most curtains, there are a few types of curtains which cannot yet be processed in a fully automatic manner by this curve cutting device.
Taking this prior art as a basis, it is a major object of the present invention to further develop a method of controlling a curve cutting device in such a way that it is also possible to cut complicated patterns.